Yield potential of ten clones from a polyclonal seedling population of Hevea brasiliensis, grown under the agro-climatic conditions of Assam in North East India were evaluated over the first eleven years of tapping along with growth at the juvenile, immature and mature phases. Out of ten preliminary selections evaluated, the highest mean dry rubber yield (g/t/t) was recorded in S2 (93.98 g) followed by S1 (88.37 g), S9 (67.92 g), S3 (63.62 g) and S10 (62.49 g) while the lowest was in S8 (49 g). All the 10 selections recorded much higher mean yield than that of the population mean (29.2 g) and RRIM 600 (44.24 g). There was considerable yield increment in the selections like S2, S1, S9, S3 and S10 in comparison with that of RRIM 600, the most popular clone in the non traditional areas. In the juvenile growth phase, at an age of three years, maximum girth was measured in S8 (34 cm) followed by S2 (29.9 cm), S3 (29.0 cm), S6 (28.6 cm) and S5 (28 cm) and the minimum was in S7 (22.9 cm) while RRIM 600 recorded a girth of 24 cm. At an age of 18 years (10 years after tapping), S2 recorded the highest girth (118.7 cm) followed by S10 (112 cm), S7 (107.1 cm), S3 (104.0 cm) and S5 (103.4 cm) and the lowest was in S1 (86.5 cm) while RRIM 600 recorded a girth of 75.1 cm. Girth increment in the ten selections during the immature andmature phases was also compared with that of the base population mean and RRIM 600. Secondary attributed like Tapping Panel Dryness (TPD), wind damage and tolerance/susceptibility to powdery mildew disease were also evaluated in the ten selections. The two top yielders, S2 and S1, were free from TPD, wind damage and also moderately tolerant to powdery mildew disease. Yield evaluation of the seedling population over eleven years indicated that all the ten selections were outstanding performers with higher yield potential than the popular clone RRIM 600 under the agro-climatic conditions of Assam. Significance of polycross progeny evaluation for non-traditional areas is discussed.